Incremental contour-extraction scheme for binary image segments
First Claim
Patent Images
1. A method for extracting contours in a digital image, the method comprising:
- performing a first one-directional pass across the digital image, the pass comprising;
i. loading rows or columns of the digital image from an external memory to a local memory,ii. identifying pixels in each row or column that correspond to a contour of an object in the digital image, andiii. adding the identified pixels to a list of contour pixels corresponding to the object for the current pass; and
iv. combining the list of contour pixels from the pass into the contour of the object; and
performing a second pass, comprising analyzing the contour pixels to classify the contour as a full closed-path contour comprising identifying an edge pixel for a first contour portion, identifying an edge pixel for a second contour portion, traversing the contour from the edge pixel of the second contour portion until finding a pixel having coordinates the same as the edge pixel for the first contour portion, identifying an overlapping portion of the first and second contour portions, and discarding the overlapping portion.
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Abstract
Contours of objects appearing in a digital image are extracted in a plurality of one-directional passes across the digital image. Each pass loads rows or columns of the image into a local memory, in the order they appear in the image, and analyzes them for the presence of portions of the full contour. The portions are then combined to create the full contour.
30 Citations
22 Claims
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1. A method for extracting contours in a digital image, the method comprising:
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performing a first one-directional pass across the digital image, the pass comprising; i. loading rows or columns of the digital image from an external memory to a local memory, ii. identifying pixels in each row or column that correspond to a contour of an object in the digital image, and iii. adding the identified pixels to a list of contour pixels corresponding to the object for the current pass; and iv. combining the list of contour pixels from the pass into the contour of the object; and performing a second pass, comprising analyzing the contour pixels to classify the contour as a full closed-path contour comprising identifying an edge pixel for a first contour portion, identifying an edge pixel for a second contour portion, traversing the contour from the edge pixel of the second contour portion until finding a pixel having coordinates the same as the edge pixel for the first contour portion, identifying an overlapping portion of the first and second contour portions, and discarding the overlapping portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for extracting contours in a digital image, the system comprising:
a local memory for storing data corresponding to the image; and
a processor comprising;i. a memory management unit for loading a portion of the image from an external memory to the local memory, and ii. an execution unit for executing instructions to (i) perform a first one-directional pass across the digital image by analyzing the portion of the image, the pass identifying a portion of a contour of an object in the digital image, (ii) combine the portions of the contour into a complete contour of the object; and
(iv) analyze the contour to classify the contour as a full closed-path contour comprising identifying an edge pixel for a first contour portion, identifying an edge pixel for a second contour portion, and in a second pass traversing the contour from the edge pixel of the second contour portion until finding a pixel having coordinates the same as the edge pixel for the first contour portion, and identifying an overlapping portion of the first and second contour portions, and discarding the overlapping portions.- View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. One or more non-transitory computer-readable storage mediums having stored thereon executable instructions operable to instruct a processor for:
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performing a first one-directional pass across the digital image, the pass comprising; i. loading rows or columns of the digital image from an external memory to a local memory, ii. identifying pixels in each row or column that correspond to a contour of an object in the digital image, and iii. adding the identified pixels to a list of contour pixels corresponding to the object for the current pass; and iv. combining the list of contour pixels from the pass into the contour of the object; and performing a second pass, comprising analyzing the contour pixels to classify the contour as a full closed-path contour comprising identifying an edge pixel for a first contour portion, identifying an edge pixel for a second contour portion, traversing the contour from the edge pixel of the second contour portion until finding a pixel having coordinates the same as the edge pixel for the first contour portion, and identifying an overlapping portion of the first and second contour portions, and discarding the overlapping portion. - View Dependent Claims (22)
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Specification